| 摘要 |
PROBLEM TO BE SOLVED: To stop the operation of a switching power supply when abnormal temperature is detected and thereafter keep the power supply from returning without increase in the number of parts. SOLUTION: Main input terminals 10 are connected with a rectifier 16 and an input smoothing capacitor 17 for rectifying and smoothing alternating current with a fuse element 15 in-between. A control circuit 18 has a switching signal generation circuit 31 including an oscillator, an overheat protection circuit 32, and a NOR circuit 33 which outputs the output signals thereof to the gate of a switching element 12. The overheat protection circuit 32 includes an overheat temperature detection circuit 32a, a restarting circuit 32b, and an RS flip flop circuit 32c. The RS flip flop circuit 32c receives output signals from the overheat temperature detection circuit 32a at a set terminal S and output signals from the restarting circuit 32b at a reset terminal R, and outputs the results of these computations to the NOR circuit 33 through an noninverting output terminal Q. COPYRIGHT: (C)2003,JPO
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